<div class="ui-grid-row-header-cell ui-grid-expandable-buttons-cell">
    <div class="ui-grid-cell-contents">
        <i ng-class="{ 'ui-grid-icon-plus-squared' : !row.isExpanded, 'ui-grid-icon-minus-squared' : row.isExpanded }"
           ng-click="grid.api.expandable.toggleRowExpansion(row.entity)"></i>
    </div>
</div>